NASA's next destination: a near-Earth asteroid?

Next giant leapWith support growing, NASA takes a small step toward walking on an asteroid

ERIC BERGER, HOUSTON CHRONICLE |
September 6, 2010

Hollywood fancies that when an asteroid threatens Earth, NASA will respond by rounding up a crew and nuking the space rock.

Before doing this, though, it would be nice to know exactly what we'd be nuking, and the fact is scientists just don't know.

But that may soon change.

There's growing support for the idea that NASA's next human flight beyond low-Earth orbit should target a near-Earth asteroid, rather than our already visited celestial neighbor, the moon.

"It's a concept that I think a lot of people can relate to," said Laurie Leshin, deputy administrator for NASA's Exploration Program.

As a destination, an asteroid appeals to NASA because it's a challenging but doable mission that will test much of the technology that would be needed for a flight to Mars.

Innumerable small asteroids, remnants from the formation of the solar system that weren't swept up by planets, glide around the sun on orbits bringing them close to Earth. About the size of a house or a small building, they could at a minimum destroy a large city on impact.

NASA has several asteroids in mind that will come within 8 million miles or so of Earth, and the space agency would like to find more. That's considerably closer than Mars, but still a few dozen times farther than the Apollo flights to the moon.

NASA could test a new generation of space capsules and rockets to ensure they can protect astronauts from space radiation and a host of other concerns that would accompany a mission, which once launched couldn't return to Earth for months.

An inside look

Such a mission also appeals to scientists, Leshin said, who know little about the interior of asteroids and would like to study large samples that could be returned.

And there's the planetary defense community, which is interested to know the interior composition of asteroids, in case one needs to be deflected.

Finally, the mission has the potential to capture the public's attention, which already has been primed to fear killer asteroids by Hollywood.

"I think this would be incredibly exciting," said Phil Plait, an astronomer who writes the popular Bad Astronomy blog. "There is inherent danger in that, of course, and any such trip would take the astronauts well past the moon. It's been decades since we've seen any long journey away from Earth.

"And the destination itself is exotic and amazing; human eyes have never seen an asteroid up close. Moreover, there's the ultimate goal of such a mission: learn more about potentially threatening objects that could one day impact the Earth and do real and serious harm to us."

2019 mission proposed

At a workshop last month in Washington, D.C., NASA canvassed the scientific, human spaceflight and planetary defense communities about their priorities for a mission to a near-Earth asteroid.

Leshin said these communities concluded that such a mission had great value but that more asteroid targets needed to be identified. Only in the last decade have targets in large numbers been found.

Earlier this year, as part of his plan to revamp human spaceflight, President Barack Obama said he wanted NASA to launch a human mission to an asteroid in 2025.

Congress has fought the president's overall plan, but a Senate version of NASA's budget appears to support an asteroid mission. Some members of the House still seem to favor a return to the moon.

The uncertainty hasn't stopped Lockheed Martin, which has a NASA contract to develop an Orion spacecraft, from developing a proposed mission to a nearby asteroid later this decade.

The plan, led by Josh Hopkins, found that an asteroid mission is possible as early as 2019 using a pair of enhanced Orion spacecraft with a two-person crew.

"Given that Orion is already in development we think it would be plausible," Hopkins said. "But it's a decision that would have to be made soon, probably within the next year."

Under the Lockheed plan, the space capsules, crammed with food, water and supplies, would launch in November 2019 and spend three months flying more than 7 million miles to an asteroid that's about 33 feet across.

Such an asteroid's gravity would be negligible, so the crew would "park" their vehicle nearby and spacewalk over, exploring and taking core samples. There would also be time to gaze homeward.

From the surface of the asteroid, Earth would probably appear as a small, bright blue and white ball, about one-eighth the diameter of the moon, Hopkins said.

After about five days the crew would climb back into one of the capsules and spend three months flying home.